A Second Neurology Story Beyond Amyloid and CGRP
While Leqembi and the CGRP class dominate neurology headlines, a quieter but commercially significant rebuild is happening in movement disorders and rare neuromuscular disease. Tardive dyskinesia, Huntington's chorea, spinal muscular atrophy (SMA) and amyotrophic lateral sclerosis (ALS) collectively affect a fraction of the patients that Alzheimer's or migraine do, but the drugs treating them now generate billions in revenue and represent some of the most mechanistically sophisticated medicine on the market, from VMAT2 inhibitors to antisense oligonucleotides to in vivo gene therapy delivered via intrathecal injection.
Tardive dyskinesia alone affects an estimated 500,000 to 800,000 people in the United States, largely as a consequence of long-term antipsychotic use in schizophrenia and bipolar disorder. Parkinson's disease affects roughly one million Americans and nearly 10 million people worldwide, with incidence rising as populations age. SMA and ALS are far smaller in absolute numbers, but their severity, orphan-drug pricing and the intensity of the underlying science make them disproportionately important to specialty pharma economics.
The Core Mechanisms
VMAT2 inhibition is the dominant mechanism in tardive dyskinesia and, increasingly, Huntington's chorea. By blocking the vesicular monoamine transporter 2, these drugs deplete presynaptic dopamine, serotonin and norepinephrine stores, reducing involuntary movements without the receptor-blocking side effects of older dopamine antagonists like tetrabenazine.
In Parkinson's disease, the therapeutic base remains levodopa-carbidopa, unchanged in principle since the 1960s but repeatedly reformulated to smooth out the pharmacokinetic swings that cause "off" periods. Extended-release capsules, continuous subcutaneous infusion and inhaled rescue formulations have all been engineered around the same core molecule rather than replacing it, because nothing has matched levodopa's efficacy at replenishing striatal dopamine.
The most consequential mechanistic shift is in genetically defined neuromuscular disease. Antisense oligonucleotides now allow direct modulation of pre-mRNA splicing to increase functional protein production, the basis for Biogen's nusinersen (Spinraza) in SMA and Biogen's tofersen (Qalsody) in SOD1-ALS. Adeno-associated virus gene therapy, delivered once via intrathecal or intravenous administration, replaces a missing or defective gene outright, the mechanism behind Novartis's onasemnogene abeparvovec (Zolgensma).
Leading Products and Manufacturers
Neurocrine Biosciences' valbenazine (Ingrezza) is the commercial leader in VMAT2 inhibition, approved for tardive dyskinesia in 2017 and later for chorea associated with Huntington's disease, generating well over $2 billion in annual sales and anchoring Neurocrine's transformation into a mid-cap neuroscience company built almost entirely on this one franchise.
Teva Pharmaceutical's deutetrabenazine (Austedo) competes directly in the same indications, and Teva has leaned on it as a growth pillar to offset generic erosion elsewhere in its portfolio, positioning Austedo alongside risperidone microspheres and its CNS-focused pipeline as evidence that the company's branded business can outlast its legacy generics franchise.
In Parkinson's, AbbVie's Duopa and Vyalev (foscarbidopa/foslevodopa), Amneal's Rytary, Supernus's Gocovri and Acorda's now-discontinued Inbrija reflect a crowded field of reformulation plays around levodopa, while Sunovion's Kynmobi and newer inhaled rescue therapies target breakthrough symptoms rather than baseline control.
In rare neuromuscular disease, Biogen's Spinraza, Novartis's Zolgensma and Roche's risdiplam (Evrysdi) now compete head to head in SMA, a market that barely existed before 2016 and now generates over $3 billion in combined annual sales despite an addressable patient population numbering in the tens of thousands globally. Biogen's Qalsody, approved in 2023 under an accelerated pathway based on neurofilament biomarker data rather than confirmed clinical benefit, represents the first approved treatment for a genetically defined ALS subtype and a template for how FDA is willing to move on ultra-rare neurodegenerative disease.
In epilepsy, SK Life Science's cenobamate (Xcopri) and UCB's Fintepla (fenfluramine) for Dravet and Lennox-Gastaut syndromes illustrate a parallel pattern: newer, narrowly targeted anticonvulsants displacing decades-old broad-spectrum agents like valproate and phenytoin, which remain cheap generics but carry teratogenicity and interaction burdens that limit their use in reproductive-age patients.
Patent Cliffs and the Generic Undercurrent
The generic core of neurology, levodopa-carbidopa, gabapentin, lamotrigine, valproate, remains almost entirely genericized and is a fixture of the FDA's chronic shortage list, particularly for injectable and extended-release formulations manufactured by a handful of players including Par, Amneal and Zydus.
The more consequential patent dynamics sit in the branded specialty tier. Ingrezza's composition-of-matter protection runs into the early 2030s, giving Neurocrine an unusually long runway relative to most single-product neuroscience companies, though Apotex and other generic filers have already challenged secondary patents. Austedo faces its own patent cliff later this decade, and Teva has been explicit with investors that maintaining exclusivity through formulation patents (Austedo XR) is central to its post-2027 revenue bridge. Zolgensma and Spinraza, as biologics and gene therapies, face a different threat: not small-molecule genericization but next-generation efficacy competition from Evrysdi's oral convenience and from newer AAV constructs in development, which is already compressing Zolgensma's growth more than any patent expiry would.
Where the Pipeline Is Heading
The next wave of CNS development is concentrating on three fronts. First, gene therapy and RNA-based medicine are moving beyond SMA and SOD1-ALS into more common genetic subtypes, with Ionis, Wave Life Sciences and uniQure advancing antisense and gene-editing programs in Huntington's disease and broader ALS genotypes. Second, next-generation VMAT2 and dopaminergic agents are being tested in earlier-stage Parkinson's and in psychiatric indications adjacent to movement disorders, extending the commercial life of a mechanism now over a decade old. Third, biomarker-driven accelerated approval, the pathway used for Qalsody and increasingly proposed for other ultra-rare neurodegenerative diseases, is becoming a template that sponsors and FDA will likely rely on again, even as it invites the same post-marketing confirmatory-trial scrutiny that has shadowed the Alzheimer's amyloid class.
The durability of this segment will depend less on a single blockbuster patent cliff than on whether payers continue tolerating orphan-drug pricing for genetically narrow populations while biosimilar and generic competition keeps compressing the older small-molecule base. Neurology's next five years will be defined by that split economy: cheap, commoditized levodopa and anticonvulsants on one side, and increasingly expensive, mechanistically precise rare-disease therapies on the other, with very little middle ground left in between.